Aqueous soap-based formulations are used as lubricants in numerous applications, in particular for providing slip and detergency on slat-, chain- or belt-type conveyors, for example, used for transporting items, such as bottles or cans, during a packaging operation. Generally, lubricating solutions are applied to such conveyors using pipe networks and suitable spray jets or nozzles. When used in hard water, soap-based lubricants generally require the addition of sequestering agents, such as EDTA, to reduce reaction between the soaps and the water hardness ions, e.g., CA.sup.2+. If adequate steps are not taken, insoluble lime soaps may be formed and blockages of the lubricant distribution system may result. Lime soap dispersing agents are also commonly used so that, if the sequestrant is insufficient or exhausted, lime soap resulting will be dispersed rather than causing immediate blockages. Generally, lime soap-dispersing surfactants, which may be nonionic, anionic or amphoteric, are included in soap-based formulations.
It has now unexpectedly been found that the above problem in the use of soap-based lubricants may be obviated and lime soap dispersion may be significantly improved by the use of a certain type of anionic surfactant in addition to those surfactants normally used in soap-based lubricants. A surprising synergism has also been noted.
The present invention relates to a synergistic aqueous soap-based lubricant composition which comprises one or more carboxylated surfactants and one or more non-carboxylated surfactants in combination with a soap.